The invention relates to a new implant device for internal-external electromyographic recording, particularly for in vivo study of the electromotor activity of the digestive system.
Almost 70% of the diseases of the gastroenteric system are classified as functional, which is to say that the cause of the patient""s problem is secondary to a malfunction of the gastroenteric canal, whether in digestive or motor terms.
The histological characteristic of a muscular component present along the entire length of the digestive system, which is responsible for its motor activity, has as its counterpart an associated electric activity that is secondary to the depolarization of the musculature itself.
They are the mirror image of one another, under both normal and pathological conditions.
The gastroenterologist""s need to study the digestive system in terms of both the electric and the motor profile (the associated electric activity) has now become imperative, since, depending on the functional or associated disturbances, there is a specific disturbance of the electromotor activity.
Electromyography is the recording of intra-cellular or extra-cellular potentials generated by cyclical electrical changes across the membranes of smooth muscle cells.
An object of the invention is to provide an apparatus which enables the study of extra-cellular potential, which is to say what can be picked up by an electrode inserted in the extra-cellular fluid circulating in the mass of smooth muscle cells and which acts as a syncytium.
Essential to that goal is insertion of the electrodes, whose number and modalities of use distinguish the recording as mono- or bipolar.
The need to study the electromotor activity of the digestive system in vivo and under conditions of freedom for the patient under study is limited by what the current technology has to offer.
The best and most reliable electromyograms of the gastrointestinal tract are obtained by serum electrodes implanted after laparotomy or laparoscopy and directly connected by means of wires to a unit for processing and visualizing the electrical signals.
Surgical implanting of electrodes is, however, not attractive to patients with suspected motor disorders, and, aside from the ethical and practical implications of recording electrical signals in a patient recently operated on and limited in his or her freedom by being anchored to wires connected to a machine, it may result in erroneous conclusions as regards normal motility.
While cutaneous electrodes of the standard gastric transducer available on the market are certainly not invasive and are practice to use, they unfortunately are still limited by the fact that they tie the patient to a machine and pen recording of only one part of the electrical activity, namely the slow wave component.
Lastly, the need to use filters to eliminate disturbances from cardiac electrical activity, from the respiratory diaphragm muscle, and from other viscera may make interpretation of the recorded image fairly operator-dependent.
Hence, the main object of the invention is to provide a new device for internal-external electromyography recording which, unlike those currently known, allows the patient to move with complete freedom during the recording and to conduct his or her life normally.
The invention also has as its object to provide a device of the abovementioned kind with a special feature of being able to be partially or fully implanted so as to reduce to a necessary minimum, if not to eliminate entirely, the fixed internal-external connected between the transducer and the units that process the set of relevant signals.
These objects are achieved in an implant device for internal-external electromyographic recording of the electromotor activity of the digestive system, which comprises at least one sensor implanted in the viscera to record its electrical activity and having means for analysis in vivo of the electric activity of the system, capable of allowing the patient normal freedom of movement.
These means can consist of at least one conversion unit to convert into radio signals the signals received from at least one sensor and to transmit such radio signals to a unit where they are processed.
At least one such sensor is an electrocatheter and the conversion unit can consist of a self-powered mobile amplifier-transmitter module connected to the electrocatheter by wires and capable of being affixed to the patient""s skin.
The module can comprise an amplifier to amplify the signals sent by the electrocatheter; a processor-converter to convert to digital signals the analog signals supplied by the amplifier;
a transmitterxe2x80x94modulator unit to convert the digital signals into radio signals and to transmit them to a fixed receiver; and an antenna that receives the radio signal transmission sent by the transmitter-modulator.
The amplifier can have an input impedance greater than or equal to 100 MOhms, as well as a gain greater than or equal to 200, and is in any case compatible with the type of microprocessor used.
The processor-converter can have a parity greater than or equal to 4 bits, an internal analog-digital converter, input-output ports as a function of the number of channels to be processed, and a full duplex UART port with internal RAM greater than 128 bytes and an external EPROM address.
The clock frequency of the processor can be greater than or equal to 2 MHz.
The fixed receiver can consist of a receiver unit for the signals captured by the antenna on the module, a comparator, a serial interface driver, and an antenna for transmission of radio signals to a unit to process and graphically visualize the signals.
The electrocatheter can be provided with one or more poles to record the electrical activity of the viscera, which is anchored by means of a removable needle.
At least one such radio signal conversion and transmission unit is combined with at least one such sensor in a device that is fully implanted in the viscera and has no connecting wires.
At least one such sensor can consist of an electrode and the radio signal conversion and transmission unit can consist of a unit that, in addition to the sensor, has an amplifier for the signals supplied by the sensor and a processor-converter directly linked to the sensor and capable of converting the analog signals from the latter into radio signals.
The device can be provided with a casing to house the unit and from which casing at least one sensor projects the minimum amount needed to ensure electrical contact with the muscle structure of the viscera. The casing on the implant device can be provided with a clip-off tip, with an end for grasping the device itself, and with wings to hold the device in the wall of the viscera.
The length and maximum lateral dimension of the casing is compatible with the operating canals of gastroscopes, the casing being made of an electrically insulating and biologically compatible material.
The device can include a self-powered mobile unit capable of being affixed to the patient""s skin, to receive radio signals sent by the unit and to transmit such signals to a fixed receiver. This mobile unit can comprise:
an antenna that receives the radio signal from the unit;
a receiver unit;
a transmitter section of the transponder which powers the unit;
a transmitter of radio signals to the fixed receiver;
a microprocessor to control and process the mobile unit; and
batteries to supply the unit.
The fixed receiver can have a unit to receive the signals sent by the mobile unit, a clipping circuit, a serial interface driver, and an antenna to transmit radio signals to a unit for processing and graphically visualizing the signals.
As regards the current technology in use, the state of the art according to the invention offers the important advantage of freeing the patient subject to internal-external electromyographic examination from being anchored by wires to the fixed part of the device.
The invention also presents the advantage of reducing, and even eliminating, the fixed connections between the internal sensors and the external signal-processing unit.
According to a preferred mode of embodiment, the invention offers the advantage of obviating the conventional need to surgically implant the means for sensing and recording gastrointestinal activity.
It should also be noted at this point that the invention, while used preferably to study the electromotor activity of the gastric viscera, is also advantageously applied to other visceral ducts of the digestive system.
Therefore, the following description of the electromyography device of the invention is not limited to the stomach.